Quantifying Spatial Variability and Its Implications on the Risk of Liquefaction at a Recently Reclaimed Site

Sites gained on the sea through near-shore reclamation are vulnerable to liquefaction in the absence of soil improvement provisions. The need, extent, and degree of such provisions are function of the assessment of liquefaction susceptibility which depends on the in situ characteristics of the fill materials. Given the nature of the materials and the process of placement, spatial variability of the soil parameters is believed to be a significant source of uncertainty that will impact the estimated risk of liquefaction and the design of liquefaction-mitigation measures. In this paper, an array of 118 boreholes with standard penetration tests performed at 1.5 m depth intervals is utilized to characterize the spatial variability in the fill across a recently reclaimed site. Conditionally-simulated random fields were used to model the spatial variability of the N-values and the fines content at the site. The randomly simulated N-values and fines content were then used as input to an SPT-based liquefaction assessment framework to assess the risk of liquefaction of different zones within the site when subjected to different seismic loading scenarios. Results of the probabilistic analysis point to the importance of modeling spatial variability using realistic random fields that reflect the uncertainty in the soil properties of the site as portrayed in the site investigation data.